Toothbrushes having a built-in reservoir for toothpaste have been previously suggested as a means for combining the features of toothbrush and toothpaste, thereby avoiding the need for carrying around or having available two separate items, the toothbrush and the toothpaste. Such a combination is considered of particular use for travelers, businessmen, children and holiday makers. Ideally such a combination, if designed correctly, would have intrinsic attractiveness and convenience attributes. Such aesthetic properties would encourage widespread use initially by people on the move, ultimately being adopted by the general population.
A survey of the prior art shows that previous inventions lack simplicity, convenience and cost effectiveness.
Thus in U.S. Pat. No. 5,026,191 to Akly, toothpaste is stored in the hollow handle of the brush and is made to flow out at the brushhead near the base of the bristles by turning a knob mounted at the opposite end of the toothbrush furthest away from the brushhead. The knob is fixed to a threaded rod mounted in the center axis of the hollow handle and when rotated causes a follower on the threaded rod to advance and force the paste via a connecting conduit in the neck and head of the brush out to the bristles. The follower is fitted with key ways, and the storage compartment corresponding key tracks, in order to prevent the follower rotating when the knob is turned. In one particular embodiment the toothpaste compartment is closed off from the conduit connecting with the brushhead by seal or valve means, such means requiring opening the seal or valve before the toothbrush can be used. Alternatively the toothbrush can be made disposable.
There are two main drawbacks with the Akly patent. Firstly, mounting the knob at the opposite end of the toothbrush (furthest from the brushhead) implies that inconvenient two-handed operation of the device will be required. The user will have to grip the toothbrush with one hand while activating the knob with the other hand. Secondly, the fact that the follower in the toothpaste compartment is mounted on a threaded rod and is fitted with key ways to prevent it rotating when the knob is turned, make sealing off and retention of the toothpaste in the storage compartment by the follower very difficult to ensure and maintain. During operation of the knob, the imperfect sealing is likely to result in leakage of toothpaste beyond the follower, either via the center hole or periphery of the follower, with consequent waste of material.
Benichou in French patent 2,592,287 disclosed a disposable toothbrush incorporating dentifrice in the handle. In this device a miniature pump, actuated hydraulically by pressing a button projecting from the end of the handle nearest the brushhead, and located in a double walled dentifrice storage compartment, causes a portion of dentifrice to emerge from the brushhead (at the bristles) via a conduit in the brush neck and brushhead. Although this disclosure does offer the convenience of operation using one hand, there are two main drawbacks. The miniature pump assembly is complex, with many moving parts, making the device uneconomical. Secondly, the need for the double wall dentifrice storage compartment and the appreciable volume of the pump itself greatly detract from the available volume of dentifrice that can be carried in a practically sized handle. For example a storage compartment of only 9 mm diameter and a dentifrice volume of only 1.5-4.5 cc are specifically referred to.
Since a dentifrice volume of 0.2 cc per teeth cleaning operation is normally required it is clear that the Benichou brush will only allow upto 22 cleaning operations. Not only is the device uneconomical, but it will only last a few applications before it must be discarded.
Laila B. Moussa in U.S. Pat. No. 5,439,014 discloses a refillable toothbrush with a liquid toothpaste reservoir. The handle of the brush is fitted with a flexible bellows and the toothbrush head with minute holes. When the bellows is depressed liquid toothpaste emerges onto the brushhead and by inverting the toothbrush so the brushhead is topmost the air pressure is balanced and the bellows re-expands. This invention has the drawback of being limited to use of a liquid dentifrice which lacks the superior teeth cleaning ability of other types. The device is cumbersome in operation since it relies on holding the toothbrush in a particular orientation during depression of the bellows, and the dentifrice may tend to dry out and block the minute delivery holes.